To prepare dough, combine the first 4 ingredients in a saucepan over medium heat, stirring until sugar dissolves. Remove from heat; cool. Dissolve yeast in warm water in a large bowl, let stand 5 minutes. Stir in sour cream mixture and 2 eggs. Lightly spoon flour into dry measuring cups; level with a knife. Gradually stir flour into sour cream mixture (dough will be soft and sticky). Cover dough; chill 8 hours or overnight.
To prepare filling; combine preserves and next 4 ingredients (preserves through 1 egg) in a medium bowl; beat with a mixer at medium speed until well blended.
Divide dough into 4 equal portions. Turn each portion out onto a lightly floured surface; knead lightly 4 or 5 times. Roll each portion into a 12x8 inch rectangle. Spread one-fourth of filling over each portion, leaving a 1/2 inch border. Starting at a long side, carefully roll up each portion "jellyroll fashion"; pinch seam and ends to seal.
Place 2 loaves on each of 2 baking sheets coated with cooking spray. Cut 4 (1/4-inch deep) "X"s in top of each loaf with scissors. Cover and let rise in a warm place (85 degrees), free from drafts, 25 minutes or until doubled in size.
Preheat oven to 375 degrees. Place 1 baking sheet in oven (cover remaining loaves to keep from drying). Bake at 375 degrees for 15 minutes or until lightly browned Repeat procedure for remaining loaves. Cool loaves slightly.
To prepare glaze, combine powdered sugar , milk and 1tsp. vanilla extract, stirring with a whisk. Drizzle warm loaves with glaze.